MSVC does not provide std::isnan so we just do provide it internally until then
MSVC does not provide std::isnan so we just do provide it internally until then

chr-engwer/Vc,VcDevel/Vc,VcDevel/Vc,chr-engwer/Vc,VcDevel/Vc,chr-engwer/Vc,VcDevel/Vc